The Human Ovarian Tissue, Oocyte, and Data Repository Core of the SCCPIR Center for Reproductive Health After Disease will expand an existing integrated network of cliniciansthe National Physicians Cooperative (NPC)which cares for patients at risk of iatrogenic infertility due to cancer treatment, and provides access to human reproductive tissues and patient data to reproductive health researchers. The Core will build on the nationwide NPC network, currently composed of 56 clinical fertility sites with a national referral mechanism that participate in an IRB-approved study protocol to perform ovarian tissue cryopreservation for young female cancer patients. The NPC provides these patients with the potential for a reproductive future and provides reproductive scientists with precious human tissue for research. The Human Ovarian Tissue, Oocyte, and Data Repository Core will leverage the successes of the NPC to increase the number of member sites, thereby expanding patient access to fertility preservation and increasing the amount of ovarian tissue available to Center researchers. While the NPC was initially developed to provide fertility preservation services to cancer patients, the expanded mission of the proposed Core is to provide quality care to a larger population of patients with diseases or undergoing treatments that may damage their reproductive health. The Core will also access human ovarian tissue and oocytes from patients who previously stored such tissues and now wish to donate them for research. Currently, these human tissues are difficult to obtain for research purposes, and the Core Repository will provide the critical bridge between clinical access to these tissues and their use in reproductive health research. Finally, the Core will develop a Data Repository to collect patient data from clinical member sites on disease diagnoses, fertility preservation counseling, and treatment information, which can be utilized by researchers to investigate clinical patterns among young patients with diseases or undergoing treatments that may impair their future reproductive health. Human ovarian tissue donated through the NPC or the new Repository Core will be applied to studies investigating new fertility preservation methods for patients who currently have no established options (Project 1) and to gain a greater understanding of the safety of experimental fertility preservation techniques (Project 11). Human oocytes from the Repository will allow researchers to identify the properties of high-quality oocytes, an integral step in advancing assisted reproductive technologies for fertility preservation patients (Project 1). Patient data acquired by the Repository Core will assist clinical researchers in the examining the fertility considerations of young patients before, during, and after disease treatment; specifically, the impact of reproductive concerns on the decision by young breast cancer patients to take adjuvant tamoxifen therapy (Project IV). This innovative Repository Core will provide human tissue and patient data essential to accelerate Center research and ultimately ensure improved clinical care for all young patients facing a loss of fertility due to diseases or their treatment.